leaking_addresses: remove command examples

[linux.git] / scripts / leaking_addresses.pl

#!/usr/bin/env perl
#
# (c) 2017 Tobin C. Harding <me@tobin.cc>
# Licensed under the terms of the GNU GPL License version 2
#
# leaking_addresses.pl: Scan 64 bit kernel for potential leaking addresses.
#  - Scans dmesg output.
#  - Walks directory tree and parses each file (for each directory in @DIRS).
#
# Use --debug to output path before parsing, this is useful to find files that
# cause the script to choke.

use warnings;
use strict;
use POSIX;
use File::Basename;
use File::Spec;
use Cwd 'abs_path';
use Term::ANSIColor qw(:constants);
use Getopt::Long qw(:config no_auto_abbrev);
use Config;

my $P = $0;
my $V = '0.01';

# Directories to scan.
my @DIRS = ('/proc', '/sys');

# Timer for parsing each file, in seconds.
my $TIMEOUT = 10;

# Script can only grep for kernel addresses on the following architectures. If
# your architecture is not listed here and has a grep'able kernel address please
# consider submitting a patch.
my @SUPPORTED_ARCHITECTURES = ('x86_64', 'ppc64');

# Command line options.
my $help = 0;
my $debug = 0;
my $raw = 0;
my $output_raw = "";    # Write raw results to file.
my $input_raw = "";     # Read raw results from file instead of scanning.

my $suppress_dmesg = 0;         # Don't show dmesg in output.
my $squash_by_path = 0;         # Summary report grouped by absolute path.
my $squash_by_filename = 0;     # Summary report grouped by filename.

# Do not parse these files (absolute path).
my @skip_parse_files_abs = ('/proc/kmsg',
                            '/proc/kcore',
                            '/proc/fs/ext4/sdb1/mb_groups',
                            '/proc/1/fd/3',
                            '/sys/firmware/devicetree',
                            '/proc/device-tree',
                            '/sys/kernel/debug/tracing/trace_pipe',
                            '/sys/kernel/security/apparmor/revision');

# Do not parse these files under any subdirectory.
my @skip_parse_files_any = ('0',
                            '1',
                            '2',
                            'pagemap',
                            'events',
                            'access',
                            'registers',
                            'snapshot_raw',
                            'trace_pipe_raw',
                            'ptmx',
                            'trace_pipe');

# Do not walk these directories (absolute path).
my @skip_walk_dirs_abs = ();

# Do not walk these directories under any subdirectory.
my @skip_walk_dirs_any = ('self',
                          'thread-self',
                          'cwd',
                          'fd',
                          'usbmon',
                          'stderr',
                          'stdin',
                          'stdout');

sub help
{
        my ($exitcode) = @_;

        print << "EOM";

Usage: $P [OPTIONS]
Version: $V

Options:

        -o, --output-raw=<file>  Save results for future processing.
        -i, --input-raw=<file>   Read results from file instead of scanning.
            --raw                Show raw results (default).
            --suppress-dmesg     Do not show dmesg results.
            --squash-by-path     Show one result per unique path.
            --squash-by-filename Show one result per unique filename.
        -d, --debug              Display debugging output.
        -h, --help, --version    Display this help and exit.

Scans the running (64 bit) kernel for potential leaking addresses.

EOM
        exit($exitcode);
}

GetOptions(
        'd|debug'               => \$debug,
        'h|help'                => \$help,
        'version'               => \$help,
        'o|output-raw=s'        => \$output_raw,
        'i|input-raw=s'         => \$input_raw,
        'suppress-dmesg'        => \$suppress_dmesg,
        'squash-by-path'        => \$squash_by_path,
        'squash-by-filename'    => \$squash_by_filename,
        'raw'                   => \$raw,
) or help(1);

help(0) if ($help);

if ($input_raw) {
        format_output($input_raw);
        exit(0);
}

if (!$input_raw and ($squash_by_path or $squash_by_filename)) {
        printf "\nSummary reporting only available with --input-raw=<file>\n";
        printf "(First run scan with --output-raw=<file>.)\n";
        exit(128);
}

if (!is_supported_architecture()) {
        printf "\nScript does not support your architecture, sorry.\n";
        printf "\nCurrently we support: \n\n";
        foreach(@SUPPORTED_ARCHITECTURES) {
                printf "\t%s\n", $_;
        }

        my $archname = $Config{archname};
        printf "\n\$ perl -MConfig -e \'print \"\$Config{archname}\\n\"\'\n";
        printf "%s\n", $archname;

        exit(129);
}

if ($output_raw) {
        open my $fh, '>', $output_raw or die "$0: $output_raw: $!\n";
        select $fh;
}

parse_dmesg();
walk(@DIRS);

exit 0;

sub dprint
{
        printf(STDERR @_) if $debug;
}

sub is_supported_architecture
{
        return (is_x86_64() or is_ppc64());
}

sub is_x86_64
{
        my $archname = $Config{archname};

        if ($archname =~ m/x86_64/) {
                return 1;
        }
        return 0;
}

sub is_ppc64
{
        my $archname = $Config{archname};

        if ($archname =~ m/powerpc/ and $archname =~ m/64/) {
                return 1;
        }
        return 0;
}

sub is_false_positive
{
        my ($match) = @_;

        if ($match =~ '\b(0x)?(f|F){16}\b' or
            $match =~ '\b(0x)?0{16}\b') {
                return 1;
        }

        if (is_x86_64()) {
                # vsyscall memory region, we should probably check against a range here.
                if ($match =~ '\bf{10}600000\b' or
                    $match =~ '\bf{10}601000\b') {
                        return 1;
                }
        }

        return 0;
}

# True if argument potentially contains a kernel address.
sub may_leak_address
{
        my ($line) = @_;
        my $address_re;

        # Signal masks.
        if ($line =~ '^SigBlk:' or
            $line =~ '^SigIgn:' or
            $line =~ '^SigCgt:') {
                return 0;
        }

        if ($line =~ '\bKEY=[[:xdigit:]]{14} [[:xdigit:]]{16} [[:xdigit:]]{16}\b' or
            $line =~ '\b[[:xdigit:]]{14} [[:xdigit:]]{16} [[:xdigit:]]{16}\b') {
                return 0;
        }

        # One of these is guaranteed to be true.
        if (is_x86_64()) {
                $address_re = '\b(0x)?ffff[[:xdigit:]]{12}\b';
        } elsif (is_ppc64()) {
                $address_re = '\b(0x)?[89abcdef]00[[:xdigit:]]{13}\b';
        }

        while (/($address_re)/g) {
                if (!is_false_positive($1)) {
                        return 1;
                }
        }

        return 0;
}

sub parse_dmesg
{
        open my $cmd, '-|', 'dmesg';
        while (<$cmd>) {
                if (may_leak_address($_)) {
                        print 'dmesg: ' . $_;
                }
        }
        close $cmd;
}

# True if we should skip this path.
sub skip
{
        my ($path, $paths_abs, $paths_any) = @_;

        foreach (@$paths_abs) {
                return 1 if (/^$path$/);
        }

        my($filename, $dirs, $suffix) = fileparse($path);
        foreach (@$paths_any) {
                return 1 if (/^$filename$/);
        }

        return 0;
}

sub skip_parse
{
        my ($path) = @_;
        return skip($path, \@skip_parse_files_abs, \@skip_parse_files_any);
}

sub timed_parse_file
{
        my ($file) = @_;

        eval {
                local $SIG{ALRM} = sub { die "alarm\n" }; # NB: \n required.
                alarm $TIMEOUT;
                parse_file($file);
                alarm 0;
        };

        if ($@) {
                die unless $@ eq "alarm\n";     # Propagate unexpected errors.
                printf STDERR "timed out parsing: %s\n", $file;
        }
}

sub parse_file
{
        my ($file) = @_;

        if (! -R $file) {
                return;
        }

        if (skip_parse($file)) {
                dprint "skipping file: $file\n";
                return;
        }
        dprint "parsing: $file\n";

        open my $fh, "<", $file or return;
        while ( <$fh> ) {
                if (may_leak_address($_)) {
                        print $file . ': ' . $_;
                }
        }
        close $fh;
}


# True if we should skip walking this directory.
sub skip_walk
{
        my ($path) = @_;
        return skip($path, \@skip_walk_dirs_abs, \@skip_walk_dirs_any)
}

# Recursively walk directory tree.
sub walk
{
        my @dirs = @_;

        while (my $pwd = shift @dirs) {
                next if (skip_walk($pwd));
                next if (!opendir(DIR, $pwd));
                my @files = readdir(DIR);
                closedir(DIR);

                foreach my $file (@files) {
                        next if ($file eq '.' or $file eq '..');

                        my $path = "$pwd/$file";
                        next if (-l $path);

                        if (-d $path) {
                                push @dirs, $path;
                        } else {
                                timed_parse_file($path);
                        }
                }
        }
}

sub format_output
{
        my ($file) = @_;

        # Default is to show raw results.
        if ($raw or (!$squash_by_path and !$squash_by_filename)) {
                dump_raw_output($file);
                return;
        }

        my ($total, $dmesg, $paths, $files) = parse_raw_file($file);

        printf "\nTotal number of results from scan (incl dmesg): %d\n", $total;

        if (!$suppress_dmesg) {
                print_dmesg($dmesg);
        }

        if ($squash_by_filename) {
                squash_by($files, 'filename');
        }

        if ($squash_by_path) {
                squash_by($paths, 'path');
        }
}

sub dump_raw_output
{
        my ($file) = @_;

        open (my $fh, '<', $file) or die "$0: $file: $!\n";
        while (<$fh>) {
                if ($suppress_dmesg) {
                        if ("dmesg:" eq substr($_, 0, 6)) {
                                next;
                        }
                }
                print $_;
        }
        close $fh;
}

sub parse_raw_file
{
        my ($file) = @_;

        my $total = 0;          # Total number of lines parsed.
        my @dmesg;              # dmesg output.
        my %files;              # Unique filenames containing leaks.
        my %paths;              # Unique paths containing leaks.

        open (my $fh, '<', $file) or die "$0: $file: $!\n";
        while (my $line = <$fh>) {
                $total++;

                if ("dmesg:" eq substr($line, 0, 6)) {
                        push @dmesg, $line;
                        next;
                }

                cache_path(\%paths, $line);
                cache_filename(\%files, $line);
        }

        return $total, \@dmesg, \%paths, \%files;
}

sub print_dmesg
{
        my ($dmesg) = @_;

        print "\ndmesg output:\n";

        if (@$dmesg == 0) {
                print "<no results>\n";
                return;
        }

        foreach(@$dmesg) {
                my $index = index($_, ': ');
                $index += 2;    # skid ': '
                print substr($_, $index);
        }
}

sub squash_by
{
        my ($ref, $desc) = @_;

        print "\nResults squashed by $desc (excl dmesg). ";
        print "Displaying [<number of results> <$desc>], <example result>\n";

        if (keys %$ref == 0) {
                print "<no results>\n";
                return;
        }

        foreach(keys %$ref) {
                my $lines = $ref->{$_};
                my $length = @$lines;
                printf "[%d %s] %s", $length, $_, @$lines[0];
        }
}

sub cache_path
{
        my ($paths, $line) = @_;

        my $index = index($line, ': ');
        my $path = substr($line, 0, $index);

        $index += 2;            # skip ': '
        add_to_cache($paths, $path, substr($line, $index));
}

sub cache_filename
{
        my ($files, $line) = @_;

        my $index = index($line, ': ');
        my $path = substr($line, 0, $index);
        my $filename = basename($path);

        $index += 2;            # skip ': '
        add_to_cache($files, $filename, substr($line, $index));
}

sub add_to_cache
{
        my ($cache, $key, $value) = @_;

        if (!$cache->{$key}) {
                $cache->{$key} = ();
        }
        push @{$cache->{$key}}, $value;
}